Pilot line processing of 18.6% efficient rear surface passivated large area solar cells

Abstract

We use the recently introduced Silicon Nitride Thermal Oxidation (SiNTO) process for the industrial fabrication of silicon solar cells that feature a thermal oxide passivated rear surface and local rear contacts. The SiNTO process represents an innovative approach for the fabrication of a passivated emitter and rear cell (PERC), since the front end part from the conventional process sequence is maintained. We apply mostly industrial production equipment using Czochralski silicon wafers that are partly processed in an industrial production line. Conventional screen printing is used for the formation of the front contacts. A stable conversion efficiency of 18.6% (independently confirmed) is achieved for a PERC device fabricated from conventional boron doped Cz-Silicon by means of the SiNTO process. The average efficiency of a batch of 24 SiNTO cells is 18.4%, measured after fabrication (not stabilized). A test module fabricated from 16 SiNTO solar cells features a fill factor of 76.2% and an open circuit voltage of 10.16 V, corresponding to an average of 635 mV per cell.